Return and buffer mechanism for automatic shooting weapons



Jan. 29, 1957 E. SAETTER-LASSEN RETURN AND BUFFER MECHANISM FOR AUTOMATIC SHOOTING WEAPONS Filed on. 16, 1955 EYLK SR TT L SSEN 2,779,249 Fatented Jan. 29, 1957 RETURN AND BUFFER MECHANISM FOR AUTO- MATIC SHUQTKNG WEAPONS The present invention relates to a recoil and butter mechanism for automatic firearms, for the return of the moveable parts which are displaced rearwardly as a result of recoil or gas pressure.

For this purpose it is known to use a helical return spring or recoil spring, which comes into action at the beginning of the backwards stroke, together with a considerably stronger spring, a so-called buffer spring which is first affected by the recoiling parts towards the end or terminal portion of the backward stroke, and which serves to effect a rapid reversal of the movement from a rearward to a forward movement.

The present invention concerns a spring mechanism of this kind which has special advantages in comparison to the hitherto known corresponding recoil and buflfer spring mechanisms. The positioning of the return or recoil spring with these known mechanisms during assembly of the weapon is difficult and takes considerable time, because after the recoiling parts have been positioned in the weapon it is necessary to position the unstressed return spring with its guide pin, if any, in such a way that it,- after assembly of the weapon, will be subjected to a definite and considerable degree of pro-stress. This is a very awkward undertaking and often leads to damage to the return spring, which during assembly tends to bend out sideways and may-kink, especially in the case of weapons where the spring is located at the rear end, for instance in a cavity in the butt. Similarly in stripping the weapon it is a great disadvantage that the spring, before it is removed, may bend out sideways and become damaged, or may, together with its guide pin, be projected forwards, so that great care and nimbleness of fingers is necessary to avoid the parts becoming lost or possibly wounding bystanders or doing other damage. The positioning of the buffer spring and its later compression, so that it is subjected to a pro-stressing, is, in the known constructions, also fairly cumbersome, and a special tool is required for pre-stressing the spring.

These disadvantages are avoided in a mechanism according to. the invention, which provides an easily positioned spring assembly, which is not awkward either during stripping or assembly of the weapon, and is simple, strong and reliable.

In accordance with the invention, there is at the rear of the weapon, for instance in the butt, a cylindrical return spring housing, which at its fore end is open and at its rear end has a base against which a pressure plate for the rear end of a return spring, positioned in the spring housing, abuts, whilst the springs front end presses against an external collar situated at the end of a telescopic recoil guide, which is fitted with a stop device to restrict its extension and is surrounded by the ecoil spring, the pressure plate being affixed to the spring guide, which is extended rearwardly and projects through an opening in the base of the spring housing, by means of which rearwardly projecting extension in conjunction with a female thread in the extension and a corresponding tensioning screw, or some other suitable tensioning de" vice, the spring guide can be retracted in the spring housing to a position determined by stop devices, at the same time firmly fastening the complete recoil spring guide with its pre-stressed recoil spring, and the spring houslng.

By these means it becomes a simple matter to assemble the recoil spring with its full degree of pre-stress on the spring guide before the assembly proper of the weapon is commenced, and it thus becomes possible to undertake assembly as well as stripping of the weapon without the compression of the return spring causing any trouble- A butter spring can in accordance with the invention be positioned around the front end of the cylindrical recoil spring housing, which also serves as a guide for butter piston or collar slidably positioned thereon in front of the buffer spring, and the rear end of the buffer spring can be surrounded by a firmly fixed cylindrical butter housing, against whose base the buffer spring presses.

This provides a very simple arrangement for guiding both the buffer spring and the buffer piston.

In cases where the butter housing is positioned on the forward end of the rearmost part of the weapon that can be removed during stripping, for instance the butt, the buffer housing, which preferably is for-med as a part of a bayonet lock for use in assembling the weapon may in accordance with the invention form a combined seat and guide bushing for the recoil spring housing, which can be introduced through the bushing from the front, and which at its front end has an external stop ring for the buffer piston positioned on the spring :housing, so that the former, when the spring housing is retracted to its final position, as determined by the abutments, compresses the buffer spring and subjects it to a certain pre-stress. Thus the butter spring will be suitably pro-stressed simultaneously with the spring housing being brought to its final position, without the use of any special appliances.

The operation of assembly and stripping of the mechanism become very simple and easy inasmuch as the abutments, which serve to limit the retraction of the recoil spring guide in the spring housing and the latters movement through the buffer housing are, in accordance with the invention, so arranged that the spring housing and the recoil spring guide are brought to their final position purely by retraction of the latter by means of threaded fastening device which secures it in the butt of the weapon.

Other features and advantages of the invention will be apparent from the following description of an embodiment of a return and bufier mechanism in accordance with the invention in connection with an automatic weapon of the recoil or gas pressure type, as shown on the drawing, where:

Fig. 1 shows partly in longitudinal section a weapon butt carrying a mechanism in accordance with the invention,

Fig. 2, a piece of the mechanism seen in longitudinal section and to larger scale,

Fig. 3, the same seen in end View, and

Fig. 4, the complete return spring guide assembly.

In Fig. 1, 1% represents a butt with a longitudinal bored out hole, comprising a forward larger portion 2, then a slightly smaller portion 3 and finally a yet narrower portion 4, which terminates in a counterbored recess 5' in the rear surface of the butt. To the ore end of the butt is afiixed a buffer housing 6 with a cylindrical wall 7 and a bushing 8 which projects into the bore or hole-portion 2. This bushing 8 has the same internal diameter as the bore or hole-portion 3. The butler housing has a bayonet weapon (not shown).

Through the bushing 8, there is from the front introduced a tubular recoil spring housing 16), which consists of a cylindrical tube 11, which at its rear end is closed by a base or plug 12, welded to the end of the housing 12, the plug 12 having a central hole. The tube 11 extends into the hole portion 3, and its diameter fits snugly in this hole portion as well as in the bushing 8, so that it is guided and supported at both ends.

In spring housing 10, there is coaxially positioned a telescopic spring guide, which consists of a. tubular or solid guide-rod 14, outside which is slidably positioned a tubular guide bushing 15. The guide-rod at its front end has a guide-head 16 attached to it by means of a transverse pin, and acting as an internal support for the slidable guide bushing, which at its rear end has an internal guide collar 17, which surrounds and is guided by the guiderod, and in conjunction with the guide-head it forms a stop for limiting extension of the spring guide. At its rear the guide-rod 3.4 has attached to it, by means of a transverse assembly pin 13, an extension 19, in the form of an extension piece, projecting rearwardly through the central hole in the spring housing base 12., and abutting against this with a pressure plate 20. The movable guide bushing has at its front end an external firmly attached collar 21, and between this and the pressure plate 2% is compressed a return spring 22, which is thus subjected to a suitable pre-stressing.

The rearwardly projecting extension 19, see Fig. 2, which extends into the hole-portion 4, has affixed at its end a threaded nipple 23, into which fits a butt-screw 24, whose head fits in the counterbored recess 5, and which, when screwed in, pulls the spring housing backwards, until an annular shoulder on the rearmost edge of a reinforcement 26 at the front of the tube 11 abuts against a forward facing face on the buffer housing 6, in which position the spring housing is seated its rearmost position.

On the tube reinforcement 26 is slid a buffer spring 28, whose rear end is surrounded by the buffer housing wall 7, and buffer springs 26 presses rearwardly against a buffer housing abutment 27, whilst its front end presses against a butter collar or piston 29, slidably mounted on the tube reinforcement 26. The buffer piston 29 has an internal collar 3%}, which, in conjunction with an external collar 31 on the tube it, acts as a stop for the butter piston and limits its forward movement. When the recoil spring housing it under the action of the screw 24, is retracted to its extreme position, the buffer spring 23 will be compressed between the buffer housing abutment 27 and the butter piston 29 and receive a suitable prestressing, to ensure a rapid reversal of the movement when the recoiling system, at the end of its recoil stroke, hits the piston 29 and further compresses the strong buffer spring. To prevent the telescopic recoil spring guide 14, 15 from turning in the spring housing tltl under the action of the butt-screw 24, and thus not being retracted, there is provided in the edge of the pressure plate 26, see Figs.- 2 and 3, a locking pin 33, which extends backwards and engages in an aperture in the spring housing base 12.

in assembling the mechanism in accordance with the invention, the return spring 22 is first positioned on the spring guide 14, 15 from which the extension 19 has previously been detached, and whilst the spring is held compressed by hand, the extension i5 is again put in position and the assembly pin it? inserted.

The spring is now mounted with its permanent prestress on the spring guide, as shown in Fig. 4. The next step is to slide the buffer piston 29 and the buffer spring 28 from the rear on to the spring housing it and the spring guide with its return spring is introduced into the spring housing with the end of the projection 19 projccting beyond its base. The spring housing etc. is new inserted from the front into the bore or hole-portions 2, 3 and 4 and the butt-screw 24 is screwed in from behind into the threaded sleeve 23 of the projection 19. Hereby the spring guide 14, 15 and therewith the recoil spring d housing 10 is retracted against the pressure of the buffer spring 29, until the parts have reached their final position. Stripping is undertaken in the opposite order.

The invention is not limited to use in connection with a butt for a weapon, and the mechanism in accordance with the invention need not--as with the embodiment shown lie at the rear of the recoiling system, but can for instance, with a view to keeping the length of the weapon down, be positioned alongside the recoiling system, or possibly be partly surrounded by these.

i claim:

1. Recoil and bufier spring mechanism, to be employed in an automatic fire weapon having a detachable butt provided with a cylindrical bore therewith, said mechanism comprising a cylindrical spring housing of such shape and dimensions as to be insertable from the front into said cylindrical bore, a telescopic recoil spring guide receivable within said spring housing a recoil spring surrounding said spring guide, means for restricting extension of said spring guide, said recoil spring thereby being held in a state of pre-stress, a pressure plate removably afiixed to the rear portion of said guide, said recoil spring having the rear end thereof abutting against said pressure plate, a stop afiixed to the front portion of said guide, said recoil spring having the front end thereof pressing against said stop, a rearward extension being provided on said spring guide and a hole being provided in the closed bottom of said spring housing, said extension fitting loosely within said hole and, upon insertion of said spring guide into said spring housing, protruding to the rear of said closed bottom, tensioning means cooperating with said protruding portion so as to retract said portion with respect to the butt, the butting of said pressure plate against the bottom of said spring housing causing the retraction of said spring housing into said bore in the butt, and said spring housing and said butt being provided with respective co-engaging abutting faces.

2. Mechanism according to claim 1, further comprising a buffer spring surrounding the front end of said cylindrical spring housing, a buffer house having a closed bottom and afhxed to the butt, the rear end of said buffer spring abutting against said bottom of said buffer house, a buffer piston slidably surrounding said spring housing to be guided thereby, the front end of said butter spring acting against said buifer piston, said buffer house being open at the front end thereof, whereby to permit insertion of said buffer spring thereinto, from the front.

3. Mechanism according to claim 2, further comprising an outer stop collar for said butter piston, positioned at the front end of said cylindrical spring housing.

4-. Mechanism according to claim 3, in which said stop collar for the buffer piston is aflixed at such a place on said spring housing that the distance between the collar and the bottom of said buffer housing with said butter spring unstressed permits the prestressing of said buffer spring by retraction of said recoil spring housing into the bore of the butt with its abutting faces engaging the corresponding abutting faces on the butt.

5. Mechanism according to claim 1, further comprising a buffer spring and a butter house surrounding the front end of said cylindrical spring housing, said buffer house having a closed bottom aflixed to the butt, the rear end of said buffer spring abutting against said bottom of said butter house, said spring housing being slidably inserted in and guiding said butter piston, the front end of said buffer spring acting against said buffer piston, said buffer house being open at the front end thereof, whereby to permit insertion of said buffer spring thereinto, from the front, said butter house being shaped as a guiding bushing for the fore end of said spring housing, said housing having at the part situated in front of said bottom of said buffer house a greater diameter than at the remaining part, the so created shoulder serving as an abutting face so as to cooperate with said bottom of said bufier house whereby to determine the retracted position of said spring housing.

6. Recoil spring mechanism for use with an automatic firearm, said firearm including automatic firing mechanism a movable portion of which'is displaced rearwardly accompanying the firing of each round, said firearm comprising a butt having a forwardly and rearwardly extending through bore formed therein, the forward portion of said bore being of larger diameter than the rearward portion thereof, said recoil spring mechanism comprising: a tubular recoil spring housing removably inserted in said bore from the front of said butt, the diameter of said housing being greater than the diameter of said rearward portion of said bore, a telescopic recoil spring guide coaxially disposed in said housing, said guide being engageable by said rearward displacement of said movable portion of said firing mechanism to shorten said guide, said guide comprising stop means for limiting the extension thereof; an extension member removably connected to the rear end of said spring guide, said extension member extending slidably through and in engagement with the rear end of said housing into said rearward portion of said bore, rearward movement of said extension memher with respect to said housing being limited by said engagement, said extension member comprising a threaded portion accessible through the rear end of said bore; a helical compression recoil spring surrounding said telescopic guide and urging said guide into its fully extended condition, the rear end of said recoil spring pressing against said extension member; threaded fastening means extending forwardly into said rear end of said bore and in engagement with said threaded portion of said extension member, said fastening means pulling said guide and said housing both rearwardly for securing the same in said butt; and seating means carried by said butt for limiting the rearward movement of said housing, whereby said recoil spring may be pre-stressed on said guide prior to the positioning of said guide in said housing and the insertion of said housing in said bore.

7. Recoil and buffer spring mechanism for use with an automatic firearm, said firearm including automatic firing mechanism a movable portion of which is displaced rearwardly accompanying the firing of each round, said firearm comprising a butt having a forwardly and rearwardly extending through bore formed therein, the forward portion of said bore being of larger diameter than the rearward portion thereof, said recoil and buffer spring mechanism comprising: a tubular recoil spring housing removably inserted in said bore from the front ofsaid butt, the diameter of said housing being greater than the diameter of said rearward portion of said bore, a tele- 6 scopic recoil spring guide coaxially disposed in said housing, said guide being engageable by said rearward displacement of said movable portion of said firing mechanism to shorten said guide, said guide comprising stop means for limiting the extension thereof; an extension member removably connected to the rear end of said spring guide, said extension member-extending slidably through and in engagement with the rear end of said housing into said rearward portion of said bore, rearward movement of said extension member with respect to said housing being limited by sad engagement, said extension member comprising a threaded portion accessible through the rear end of said bore; a helical compression recoil spring surrounding said telescopic guide and urgfng said guide into its fully extended condition, the rear end of said recoil spring pressing against said extension member; threaded fastening means extending forwardly into said rear end of said bore and in engagement with said threaded portion of said extension member, said fastening means pulling said guide and said housing both rearwardly for securing the same in said butt; a collar slidably mounted on the forward end of said housing; further stop means carried by said housing for limiting forward movement of said collar, said collar being adapted for engagement by said movable portion of said firing mechanism during the terminal portion of its rearward movement; a relatively stiif buffer spring surrounding the forward end of said housing, said buifer spring pressing said collar forwardly with respect to said butt, said buffer spring being pre-stressed by said threaded fastening means to urge said collar yieldingly into engagement with said "further stop means, said recoil spring individually yieldingly opposing the initial portion and said buffer spring and recoil spring jointly opposing the terminal portion of said rearward movement of said movable portion of said firing mechanism; and seating means carried by said butt for limiting the rearward movement of said housing, whereby said recoil spring may be pre-stressed on said guide prior to the positioning of said guide in said housing and the insertion of said housing in said bore and said buffer spring may be pre-stressed by tightening said threaded fastening means after insertion of said recoil spring housing in said bore.

References Cited in the file of this patent UNITED STATES PATENTS 1,019,937 Whittier Mar. 12, 1912 2,093,169 Halek Sept. 14, 1937 2,144,951 Williams Jan. 24, 1939 2,379,461 Simpson July 3, 1945 

